Most traders in Afghanistan are from the Pashtun Belt. With the border closed, they have suffered severe financial losses, which has turned them against the Taliban as well. After the establishment of terrorist camps, Pakistan's border closure, and measures to return refugees, a perception has emerged there that this regime's continued existence might even erase Afghanistan from the world map.
Taliban may think they will trade through Iran or central asian states but with borders with Pakistan closed, its afghan pashtun trader that will suffer.